The time-limited dispatch (TLD) of aircraft allows operators to efficiently meet
certification requirements. In order to display that these requirements are met it is
necessary to model the aircraft systems to which TLD is being applied. Currently
variations of fault tree analysis and Markov analysis are commonly used. However, in
order to apply either of these methods a number of assumptions are made in order to
assist in the analysis. Monte Carlo simulation (MCS) is presented here as an
alternative method of demonstrating the required level of system reliability. A simple
system is analysed using a time-weighted average approach, a reduced fault state
Markov approach and a MCS approach. MCS is seen to offer benefits when
modelling the application of TLD to a simple system that could also be seen in the
modelling of the application of TLD to real aircraft systems.